A modified physiological strain index for workplace-based assessment of heat strain experienced by agricultural workers.

BACKGROUND: As global temperatures rise, increasing numbers of individuals will work in hot environments. Interventions to protect their health are critical, as are reliable methods to measure the physiological strain experienced from heat exposure. The physiological strain index (PSI) is a measure of heat strain that relies on heart rate and core temperature but is challenging to calculate in a real-world occupational setting. METHODS: We modified the PSI for use in field settings where resting temperature and heart rate are not available and used the modified physiological strain index (mPSI) to describe risk factors for high heat strain (mPSI ≥ 7) experienced by agricultural workers in Florida during the summers of 2015 through 2017. mPSI was calculated for 221 workers, yielding 465 days of data. RESULTS: A higher heat index (ß = 0.185; 95% CI: 0.064, 0.307) and higher levels of physical activity at work (0.033; 95% CI: 0.017, 0.050) were associated with a higher maximum mPSI. More years worked in US agriculture (-0.041; 95% CI: -0.061, -0.020) were protective against a higher maximum mPSI. Out of 23 workdays that a participant experienced a maximum mPSI ≥ 7, 22 were also classified as strained by at least one other measure of high heat strain (core temperature [Tc] >38.5°C, sustained heart rate >(180 - age), and mean heart rate > 115 bpm). CONCLUSIONS: This study provides critical information on risk factors for elevated heat strain for agricultural workers and suggests a practical approach for using PSI in field-based settings.

Risk Factors for Reaching Core Body Temperature Thresholds in Florida Agricultural Workers.

BACKGROUND: There is a compelling need to identify agricultural workers at risk for heat related illness (HRI). METHODS: Data from Florida agricultural workers (N = 221) were collected over 3 summer workdays (2015 to 2017) to examine risk factors for exceeding NIOSH-recommended core temperature (Tc) thresholds (38 °C [Tc38] and 38.5 °C [Tc38.5]) using generalized linear mixed models. RESULTS: On an average workday, 49% of participants exceeded Tc38 and 10% exceeded Tc38.5. On average, participants first exceeded both thresholds early in the day; the Tc38 threshold mid-morning (10:38 AM), and Tc38.5 about a half hour later (11:10 AM). Risk factors associated with exceeding Tc38 included years working in US agriculture, body mass index, time performing moderate-to-vigorous physical activity, increasing heat index, and field crop work. CONCLUSIONS: The high prevalence of core temperatures exceeding recommended limits emphasizes the serious need for mandated HRI prevention programs for outdoor workers.

Physical activity and work activities in Florida agricultural workers.

BACKGROUND: Laboring in hot and humid conditions is a risk factor for heat-related illnesses. Little is known about the amount of physical activity performed in the field setting by agricultural workers, a population that is among those at highest risk for heat-related mortality in the United States. METHODS: We measured accelerometer-based physical activity and work activities performed in 244 Florida agricultural workers, 18 to 54 years of age, employed in the fernery, nursery, and crop operations during the summer work seasons of 2015-2017. Environmental temperature data during the participant's workdays were collected from the Florida Automated Weather Network and used to calculate wet bulb globe temperature (WBGT). Generalized linear mixed model regression was used to examine the association between WBGT on physical activity, stratified by the agricultural sector. RESULTS: Fernery workers had the highest overall volume of physical activity, spending nearly 4 hours in moderate to vigorous activity per workday. Activity over the course of the workday also differed by the agricultural sector. A reduction on average physical activity with increasing environmental temperature was observed only among crop workers. CONCLUSIONS: The quantity and patterns of physical activity varied by the agricultural sector, sex, and age, indicating that interventions that aim to reduce heat-related morbidity and mortality should be tailored to specific subpopulations. Some workers did not reduce overall physical activity under dangerously hot environmental conditions, which has implications for policies protecting worker health. Future research is needed to determine how physical activity and climatic conditions impact the development of heat-related disorders in this population.

Hydration Status, Kidney Function, and Kidney Injury in Florida Agricultural Workers.

OBJECTIVE: Recent findings suggest that laboring in hot occupational environments is related to kidney damage in agricultural workers. We examined hydration status and kidney function in 192 Florida agricultural workers. METHODS: Blood and urine samples were collected over 555 workdays during the summers of 2015 and 2016. Urine-specific gravity (USG), serum creatinine, and other kidney function markers were examined pre- and post-shift on each workday. Multivariable mixed modeling was used to examine the association of risk factors with hydration status and acute kidney injury (AKI). RESULTS: Approximately 53% of workers were dehydrated (USG ≥1.020) pre-shift and 81% post-shift; 33% of participants had AKI on at least one workday. The odds of AKI increased 47% for each 5-degree (°F) increase in heat index. CONCLUSION: A strikingly high prevalence of dehydration and AKI exists in Florida agricultural workers.

Classification of Heat-Related Illness Symptoms Among Florida Farmworkers.

BACKGROUND: Farmworkers working in hot and humid environments have an increased risk for heat-related illness (HRI) if their thermoregulatory capabilities are overwhelmed. The manifestation of heat-related symptoms can escalate into life-threatening events. Increasing ambient air temperatures resulting from climate change will only exacerbate HRI in vulnerable populations. We characterize HRI symptoms experienced by farmworkers in three Florida communities. METHODS: A total of 198 farmworkers enrolled in 2015-2016 were asked to recall if they experienced seven HRI symptoms during the previous work week. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between selected sociodemographic characteristics and reporting three or more symptoms. Latent class analysis was used to identify classes of symptoms representing the HRI severity range. We examined sociodemographic characteristics of the farmworkers across the latent classes. RESULTS: The mean age (±SD) of farmworkers was 38.0 (±8) years; the majority were female (60%) and Hispanic (86%). Most frequently reported symptoms were heavy sweating (66%), headache (58%), dizziness (32%), and muscle cramps (30%). Females had three times the odds of experiencing three or more symptoms (OR = 2.86, 95% CI 1.18-6.89). Symptoms fell into three latent classes, which included mild (heavy sweating; class probability = 54%), moderate (heavy sweating, headache, nausea, and dizziness; class probability = 24%), and severe (heavy sweating, headache, nausea, dizziness, muscle cramps; class probability = 22%). CONCLUSIONS: Farmworkers reported a high burden of HRI symptoms that appear to cluster in physiologic patterns. Unrecognized accumulation of symptoms can escalate into life-threatening situations if untreated. Our research can inform interventions to promote early recognition of HRI, on-site care, and appropriate occupational health policy. Administrative or engineering workplace controls may also reduce the manifestation of HRI. CLINICAL RELEVANCE: This study advances the current knowledge of HRI symptoms in farmworkers and moves beyond reporting individual symptoms by utilizing latent class analysis to identify how symptoms tend to co-occur together in this population. It acknowledges multiple symptoms occurring as a result of occupational heat exposure and highlights the importance of symptom recognition.

Caring for Children While Working in Agriculture-The Perspectiveof Farmworker Parents.

Access to safe, off-farm childcare is often a challenge for farmworkers with young children and is likely to become an increasingly salient barrier as more agricultural workers migrate together with families and as the number of women entering the agricultural workforce increases. Agriculture is one of the most hazardous industries, and the presence of young children in the workplace puts them at risk. To better understand the current nature of childcare for farmworker families and the challenges to accessing services, this project facilitated in-person surveys with 132 parents in three communities in Florida. A convenience sample that intentionally targeted parents living and working in areas with limited access to Migrant and Seasonal Head Start facilities was used to recruit participants. Most participants reported childcare access as a challenge. They expressed a desire to work in an area based on childcare availability. These findings offer agribusiness leaders important data to consider. They also suggest that industry support of childcare may be an important workforce investment. Findings indicate that high quality, affordable off-farm childcare services could serve as a means for attracting farmworkers to regions currently experiencing labor shortages. Additional research is warranted to explore this subject in diverse geographic areas.

Acute Illness Associated with Exposure to a New Soil Fumigant Containing Dimethyl Disulfide-Hillsborough County, Florida, 2014.

Dimethyl disulfide (DMDS) is a new soil fumigant that is considered a replacement for methyl bromide. In 2014, the Florida Department of Health (FDOH) received several complaints of illness following a strong DMDS odor in Hillsborough County. Public health investigation of DMDS-related illness was conducted to assess illness and identify areas to target for prevention activities. This investigation included surveillance, interviews, review of medical records, review of supporting documentation, and determination of pesticide-related illness and injury case status. FDOH interviewed 66 people complaining of illness related to DMDS. Thirty-two were classified as possible and 11 as suspicious cases of DMDS-related illness. Among cases, the mean age was 48 years (range: 3-71 years). The majority were non-Hispanic (n = 43, 100%), white (n = 40, 93%), and female (n = 23, 53.5%). The most common signs and symptoms reported by exposed people included eye pain, throat irritation, nausea, dizziness, headache, and fatigue. There were 88% of cases classified as having low severity of illness and 12% classified as having moderate severity. The average distance from an application site among individuals who reported being exposed at or near their home was 0.74 miles for those classified as cases (n = 36) and 2.84 miles for those not classified as cases (n = 21, P < .05). This is the first known comprehensive report of DMDS-related illness in humans. Even though illnesses associated with DMDS in this investigation were generally of low severity, it is important to identify better ways to prevent off-target movement of DMDS and to improve notification to communities when nearby DMDS applications are planned.